This is what I would do. I would pull the bullet from one of those cartridges and remove the powder. Then I would try to chamber it, using a REASONABLE amount of force to close the bolt. If it doesn't close - go back to square one. But if it closes, I would extract it. I would look at it closely to see where it is meeting resistance. I would load it with a small amount of powder and a wax plug. Then I would put it back in the chamber and fire it. Whatever the chambering, it would fire-form your case so you would know for sure.